Purification of sulphur dioxide



C. M. BULLARD.

PURIFICATION OF SULPHUR DIOXIDE. APPLICATION FILED 050.4, 1920. RENEWED FEB. 18, I922.

1,%10,585, Patented Mar. 21, 1922.

. izizflezfi CHARI-E M. BULLAKD, E I a CEARLES M. BULLARD, OF AEPLETON, WISCONSIN.

PURIFICATION OF SULPH UR DIOXIDE.

Application filed. December 4, 1920, Serial No. 428,411.

'useful Improvements in thePurification of Sulphur Dioxide, of which the following is a specification.

In pulp makin SO gas, it is we duced and in the production of 1 known that S0 is'proas an impurity in the S0 gas and it is highly desirable to remove this impurity before the S0 goes to the absorption system, so this invention relates to the purification of the S0 gas.

The invention consists essentially of passing the impure gas as it comes from the cooler or other source through a tower in which it encounters sprays of water, which sprays absorb the S6 but permit the purified S0 gas to pass through. The water, and SO, absorbed therein, are collected and heated t drive off any SO gas which may have become absorbed, this SO gas being led back to the cooler or elsewhere, and the weak liquid SO (or H SO that it then be- .comes) is discharged. This method can be adapted to have all these steps take place continuously if desired.

The invention has been illustrated by showing and describing one embodiment thereof, namely, the best of which I am at present informed, but it is to be understood that the invention is capable of many other embodiments and that the one shown is used in an illustrative and not a limiting sense.

In the drawings, Figure 1 shows a side elevation of my device and Figure 2 a detail.

In the drawings, the numeral 11 indicates a pipe which containsthe gas from the cooler or other source. This gas is principally S0 but it has SO, in it as an impurity. The gas goes t a tower 12 where it passes upwardly therethrough and in which it is purified of its S0 and exits throughoutlet 13. In the upper part of the tower 12, I provide a plurality of spray nozzles 14: which depend from pipes 15 extending across the tower, which pipes are controlled by a valve 16 and which pipes have water fed to them from a conduit 17 in circuit with which is ump 18, In the bottom of the tower isa iquid reservoir. 19, the normal liquid level of which is indicated by a dotted line 20. 21 indicates a gauge glass to show the liquid level. The pump 18 isadapted to take liquid from Specification of Letters Fatent.

the reservoir 19 Renewed February 18, 1922. Serial n6. 5353662.

by means of outlet 22 and elevate it to may also supply a small stream of the liquid in reservoir 19 to a distilling apparatus 23 through the medium of a pipe 24 which is controlled by valve 25.

The distilling apparatus 23 consists of a fairly shallow tank 26 having in the bottom thereof a steam coil 27, the steam coil having an inlet 28 and an outlet 29.. Theliquid 1n the tank can be removed by valved outlet 30 and the gasified S0 leaves the distilling apparatus through conduit 31 which carries it back to the cooler or elsewhere.

32 indicates a'moisture separator in the gas outlet 13 and 33 represents the moisture drip. 34: is a duct leading toan SO detector. 35 represents a fresh water inlet to the liquid reservoir. In operation the gas with its impurity'comes from the cooler or other source through the inlet pipe 11 and passes upwardly through the tower 12 where it meets the water -in spray form passing downwardly or in a direction opposite to the flow of the gas. This water in spray form com pletely fills thetower sothat it is impossible or next to impossible for the gas to get through the tower without coming in contact'with some particles of water and these particles of water are depended upon to absorb the impurity in the gas, namely S0 so that the gas which passes through the outlet, 13 is practically pure S0 and any moisture remaining in the purified gas is removed therefrom by the moisture separator 32, so that the SO gas, purified and dried, passes to the absorption system. The falling preferably liquid collected in the reservoir 19 gradually becomes saturated with the SQ, so it becomes necessary to remove the saturated liquid to the distilling apparatus 23 where, by means of heat supplied by coil 27, any remaining S0 is through exit 31 back to the cooler or elsewhere and the reniainine" liquid discharge saturated witlrSO is driven of? through outlet 30. a

' Until the liquid in the reservoir 19 be- 2 comes saturated, pump 18 draws it out of the reservoir and forces it up through the sprays. The adding of fresh water and the purification of the saturated water in the reservoir can take place intermittently, or the i valve 25, the valve in the fresh water inlet 35, and the valve 30 may-be cracized so the sprays 14:. The pump 18 gasified and driven off Patented Mar. 21, 11922.

that the water in the reservoir is being conin passing the gas upwardly through a fallstantly freshened and constantly fed to the ing absorbing medium, whereby the medium distilling apparatus. I absorbs the impurity and a portion of the It will thus be seen that Lhave devised S0 collecting the absorbing medium and 5 a very simple apparatus for removing the removing from it any of the S0 it may have 15 impurity from S0 gas, one that is cheap to absorbed. build and, yet very efficient in operation. In testimony whereof I have affixed my What I claim is: signature to this specification. A method of purifying gaseous SO hav- I 10 ing gaseous SO as an impurity, consisting CHAS. M. BULLARD. 

